The Stovebolt Site Forums The Shop Area The HiPo Shop v6 swap

I have a 46, what all is necessary for a v-6 swap. Probably 4.3 L

depends on if it injected or not....
rear end and trans for sure (unless you're gonna run the stock trans)..
if it's gonna be injected, you'll need to rewire the truck.
6 volts ain't gonna work at all.
we gonna need specifics, ya know?

btw, where in nebraska?

tomslik

Western part--Scottsbluff
b51r

Keep me posted. I have a 51 GMC panel and a low mileage 4.3 Vortec in my shop. I was thinking the same thing.

Thanks

I am also getting ready sometime this spring to intall a 4.3 v6, 700r4 trans & 69 Olds rear end (273 gears) in my 49 chevy 5 window.
This is a throttle body set with a computor.
I am hoping that I can get a wiring harness from a company like EZ wiring.
Has anyone out ever put this set up together?

painless makes a wiring kit (well worth the $$ imo)
but you're gonna hate the 2.73's with the od trans...
i'd start at a set of 3.73's...

Thanks very much for the heads up and info on the wiring harness.
The motor and trans came out of a 92 Astro as one unit.
Why the 3.73's? & not the 2.73's.?
Originally my intentions were to have a highway type gearing for cruising on long trips.
I am new at this and sure appreciate the imput.

The 2.73's in OD would give you a final drive of 1.91. Couldn't climb hills or even buck a headwind with this. The 3.73's in OD are a final of 2.61--much more practical.

...and depending on the final tire diameter, you may wanna go deeper yet.

i've put 4.56's in a 72 chevy with 30" tall tires.
here's a ballpark way to get close on the gears,
after you get it running,drop the trans down in 3rd (1 to 1 ratio,not od) and see what the tach sez.you wanna shoot for around 3000 rpm at 60 mph.

you MAY wanna go the next step down in gears with that 4.3 as they really don't have the power of a v8(don't get me wrong, i LIKE 4.3's)

there's programs on the net for this but i can't find the link.
try a search for bowling automotive math...

turning too slow down the highway is just as bad as too fast, it'll eat just as much fuel...

hello vickraft, i've got a 99 silverado with the 4.3v6 and the 5 speed overdrive tranny. in fourth gear at about 2000 rpm, i'm going about 65 mph. and it has power to climb hills or pass and go faster if i need it . but, 5th gear is useless below 70plus mph. i don't use it unless there is a straight stretch and no officers in sight. the rearend is a 3.23 ratio, and i wish now that it was a 3.73. hope this helps.

HiFellow Stovebolters,coilover,tomslick,garyg.
Thanks for helping me do it right the first time. Until the engine & trans. are installed I can only sort of guess at the RPM etc. but I did do some what ifs?
Tom ,on the wiring harness question. Painless Wiring is sending a cataloque and have the part I need to do the job. I found the site you mentioned to calculate gears for differentials etc. This is a fantastic site for Auto tech. cal/info. www.bgsoflex.com
The site did the calculations based on my entries on the following. MPH 60, Tire Dia. 15", Peak Horspower @2000 . results for best Diff. gear ratio was 2.23 to 1.
1. Is this a 2:23 gear ratio differential?
2. Also I have access to a 2.53 rear gear assembly that is the right width. Would this work?
3. Do lower number ratio's mean I need more power?
4. If the number is higher such as a 373 that garyg & coilover mentions can I upgrade the excisting rear end to the right numbers?
I should have checked the ratio that was in the donner 92 Astro. (6 passenger std lenght body) Would anybody know the ratio for this vehicle?

I am not the author but I really think this fits.
Enthusiasm without knowledge is like running in the dark.

Just noticed that you referred to the tire dia as 15". The formula is probably asking for outside tire diameter which would be more like 26" plus depending on the tire you are running. Might want to recheck. I don't think you want a rearend with less than 3.43 gears with the OD transmission. The lower the gear ratio number the higher the rearend gears which equals less torque.

Just for additional reference I am running a 3.43 rearend in my 49 with a 350V8 and 350 Turbo transmission. At 65mph the tach reads 3200 rpm which I feel is too many rpm for a long highway trip. In April I will install a 2004R overdrive tranny and the rpm should drop to about 2000 at 65mph which also should give me better gas mileage.

I have a 03 Safari with the 4.3. I had a 00 Jimmy with the 4.3. Don't get me wrong, it's not a bad motor, but there won't be much of a signicant gain if any over the amazingly simple inline. You won't get better gas mileage, just the smog control maybe. Btw the van gets 13 mpg and the Jimmy got 15 - 17. To save money, a 350 with tall gears would get as good or better mileage AND have a lot more power. Better yet and way more cool would be a hopped up inline 235, 261, 250, 292 or 302 with the proper tranny, tires and gearing. Just my extremely biased opinion.